Blood platelets play a critical role in the prevention of excessive blood loss at sites of tissue injury. They are formed from megakaryocytes in the bone marrow and circulate in the blood in a resting state, but undergo 'explosive' activation upon damage to the vasculature, supporting formation of a vascular plug. Conditions associated with a reduction in platelet number can lead to excessive bleeding. Platelets play a fundamental role in stroke and myocardial infarction, and contribute to the metastatic spread of cancer. The Gordon Research Conference (GRC) on the Cell Biology of Megakaryocytes and Platelets is the leading scientific meeting focused on the biology of platelets and their precursor cells, megakaryocytes. This will be the 6th biennial meeting that brings together two groups of scientists with complimentary goals and interests. Meeting topics will include emerging roles for platelets in biology, including immunity, tumor metastasis, and lymphatic development. Identification of novel signaling pathways that regulate MK development and platelet activation will also be a key theme, including an original session focused on membrane biology. Novel mechanisms for growing platelets in vitro as well as innovative ways to visualize MK and platelet biology will also come under the spotlight. The conference will also report on the latest findings in the regulation of circulating platelet numbers. In addition, there is a whole session devoted to presentations of Hot Topics, selected form submitted abstracts. There are several innovative aspects to the planned meeting, including 1. A session titled Blood Pharming: Making platelets in vitro, providing opportunities to learn about, and discuss new ideas about how novel megakaryocyte and platelet biology may transform the transfusion industry; 2. The sessions will combine both MK and platelet development and function, thus, forcing a union of two audiences with overlapping interests, further increasing exchange of ideas; 3. The bench to bedside potential is illustrated in a new session titled: Megakaryocytes and platelets breaking bad, and talks, such as on novel therapeutic options for low platelet counts; and 4. Inclusion, for the firs time, of a session titled: Platelets as the Swiss Army Knives of the Blood provides opportunities to learn about, and discuss new roles for platelets in other fields. The retention of the Gordon Research Seminar (GRS) for the 2015 meeting is a critical component. This venue encourages promising trainees to participate more visibly in the program and possibly be encouraged to continue and develop a career in MK and platelet biology. Abstracts submitted by trainees will be scored by a panel, and selected for oral presentations, of which some will also present under Hot Topics in the GRC. Open discussions with investigators will provide mentoring related to careers in academia and in pharmaceutical companies. The GRS/GRC take place from April 18-19th and 19-24th, 2015, at the Renaissance Tuscany II Ciocco Resort, Lucca (Barga), Italy.